The first sputnik
thumb|300px|rightSputnik 1 (Russian: "Cпутник-1" Russian pronunciation: [ˈsputʲnʲək], "Satellite-1", ПС-1 (PS-1, i.e. "Простейший Спутник-1", or Elementary Satellite-1)) was the first artificial satellite to be put into Earth's orbit. It was launched into an elliptical low Earth orbit by the Soviet Union on 4 October 1957, and was the first in a series of satellites collectively known as the Sputnik program. The unanticipated announcement of Sputnik 1's success precipitated the Sputnik crisis in the United States and ignited the Space Race within the Cold War. The launch ushered in new political, military, technological, and scientific developments. While the Sputnik launch was a single event, it marked the start of the Space Age.[1] Apart from its value as a technological first, Sputnik also helped to identify the upper atmospheric layer's density, through measuring the satellite's orbital changes. It also provided data on radio-signal distribution in the ionosphere. Pressurized nitrogen in the satellite's body provided the first opportunity for meteoroid detection. If a meteoroid penetrated the satellite's outer hull, it would be detected by the temperature data sent back to Earth[citation needed]. Sputnik 1 was launched during the International Geophysical Year from Site No.1, at the 5th Tyuratam range, in Kazakh SSR (now at the Baikonur Cosmodrome). The satellite travelled at 29,000 kilometers (18,000 mi) per hour, taking 96.2 minutes to complete an orbit, and emitted radio signals at 20.005 and 40.002 MHz[2] which were monitored by amateur radio operators throughout the world.[3] The signals continued for 22 days until the transmitter batteries ran out on 26 October 1957.[4] Sputnik 1 burned up on 4 January 1958, as it fell from orbit upon reentering Earth's atmosphere, after travelling about 60 million km (37 million miles) and spending 3 months in orbit.[5] Before the launch thumb|300px|right|videoSatellite construction project The history of the Sputnik 1 project dates back to 27 May 1954, when Sergei Korolev addressed Dmitriy Ustinov, then Minister of Defence Industries, proposing the development of an Earth-orbiting artificial satellite. Korolev also forwarded Ustinov a report by Mikhail Tikhonravov with an overview of similar projects abroad.[6] Tikhonravov emphasized that an artificial satellite is an inevitable stage in the development of rocket equipment, after which "interplanetary communication" would become possible.[7] On 29 July 1955 the U.S. President Dwight Eisenhower announced, through his press secretary, that the United States would launch an artificial satellite during the International Geophysical Year (IGY).[8] A week later, on 8 August the Presidium of the Central Committee of the CPSU approved the idea of creating an artificial satellite.[9] On 30 August Vasily Ryabikov – the head of the State Commission on R-7 rocket test launches – held a meeting where Korolev presented calculation data for a spaceflight trajectory to the Moon. They decided to develop a three-stage version of the R-7 rocket for satellite launches.[10] http://en.wikipedia.org/wiki/File:Sputnik_Arming_Key.jpgThis metal arming key is the last remaining piece of the first Sputnik satellite. It prevented contact between the batteries and the transmitter prior to launch. Currently on display at the Smithsonian National Air and Space Museum.On 30 January 1956 the Council of Ministers approved practical work on an artificial Earth-orbiting satellite. This satellite, named "Object D", was planned to be completed in 1957-58; it would have a mass of 1,000 to 1,400 kg (2,200 to 3,090 lb) and would carry 200 to 300 kg (440 to 660 lb) of scientific instruments.[11] The first test launch of "Object D" was scheduled for 1957.[7] According to that decision, work on the satellite was to be divided between institutions as follows:[12] *USSR Academy of Sciences was responsible for the general scientific leadership and research instruments supply *Ministry of Defence Industry and its main executor OKB-1 were assigned the task of creating the satellite as a special carrier for scientific research instruments *Ministry of Radiotechnical Industry would develop the control system, radio/technical instruments and the telemetry system *Ministry of Ship Building Industry would develop gyroscope devices *Ministry of Machine Building would develop ground launching, refueling and transportation means *Ministry of Defence was responsible for conducting launches By July 1958 the draft was completed and the scientist tasks to be carried out by a satellite were defined. It included measuring the density of the atmosphere, its ion composition, corpuscular solar radiation, magnetic fields, cosmic rays, etc. Data, valuable in creating future satellites, was also to be collected. A ground observational complex was to be developed, that would collect information transmitted by the satellite, observe the satellite's orbit, and transmit commands to the satellite. Such a complex should include up to 15 measurement stations. Because of the limited time frame, they should have means designed for rocket R-7 observations. Observations were planned for only 7 to 10 days and orbit calculations were expected to be not quite accurate.[13] Unfortunately, the complexity of the ambitious design and problems in following exact specifications meant that some parts of 'Object D', when delivered for assembly, simply did not fit with the others, causing costly delays. By the end of 1956 it became clear that plans for 'Object D' were not to be fulfilled in time because of difficulties creating scientific instruments and the low specific impulse produced by the completed R-7 engines (304 sec instead of the planned 309 to 310 sec). Consequently the government re-scheduled the launch for April 1958.[7] Object D would later fly as Sputnik 3. Fearing the U.S. would launch a satellite before the USSR, OKB-1 suggested the creation and launch of a satellite in April–May 1957, before the IGY began in July 1957. The new satellite would be simple, light (100 kg or 220 lb), and easy to construct, forgoing the complex, heavy scientific equipment in favour of a simple radio transmitter. On 15 February 1957 the Council of Ministers of the USSR approved this, providing for launching the simplest version satellite, designated 'Object PS'.[14] This version also facilitated the satellite to be visually tracked by Earth-based observers while in orbit, and transmit tracking signals to ground-based receiving stations.[14] Launch of two satellites PS-1 and PS-2 with two R-7 rockets (8K71) was allowed, but only after one or two successful R-7 test launches.[14] Design http://en.wikipedia.org/wiki/File:Sputnik_asm.jpg http://en.wikipedia.org/wiki/File:Sputnik_asm.jpgA replica of Sputnik 1 at the U.S. National Air and Space MuseumThe chief constructor of Sputnik 1 at OKB-1 was M.S.Khomyakov.[28] The satellite was a 585 mm (23 in) diameter sphere, assembled from two hemispheres which were hermetically sealed using o-rings and connected using 36 bolts.[29] The hemispheres, covered with a highly polished 1 mm-thick heat shield[30] made of aluminium-magnesium-titanium AMG6T ("AMG" is an abbreviation for "aluminium-magnesium" and "T" stands for "titanium", the alloy contains 6% of magnesium and 0.2% of titanium[31]) alloy, were 2 mm-thick.[32] The satellite carried two antennas designed by the Antenna Laboratory of OKB-1 led by M.V.Krayushkin.[12] Each antenna was made up of two whip-like parts: 2.4 and 2.9 metres (7.9 and 9.5 ft) in length,[33] and had an almost spherical radiation pattern,[34] so that the satellite beeps were transmitted with equal power in all directions; making reception of the transmitted signal independent of the satellite's rotation. The whip-like pairs of antennas resembled four long "whiskers" pointing to one side, at equal 35 degrees angles with the longitudinal axis of the satellite.[35] The power supply, with a mass of 51 kg (110 lb),[36] was in the shape of an octahedral nut with the radio transmitter in its hole.[37] It consisted of three silver-zinc batteries, developed at the All-Union Research Institute of Current Sources (VNIIT) under the leadership of N. S. Lidorenko. Two of them powered the radio transmitter and one powered the temperature regulation system.[36] They were expected to fade out in two weeks, but ended up working for 22 days. The power supply was turned on automatically at the moment of the satellite's separation from the second stage of the rocket.[35] The satellite had a one-watt, 3.5 kg (7.7 lb)[21] radio transmitting unit inside, developed by V. I. Lappo from NII-885,[35] that worked on two frequencies, 20.005 and 40.002 MHz. Signals on the first frequency were transmitted in 0.3 sec pulses (under normal temperature and pressure conditions on-board), with pauses of the same duration filled by pulses on the second frequency.[38] Analysis of the radio signals was used to gather information about the electron density of the ionosphere. Temperature and pressure were encoded in the duration of radio beeps, which additionally indicated that the satellite had not been punctured by a meteorite. A temperature regulation system contained a fan, a dual thermal switch, and a control thermal switch.[35] If the temperature inside the satellite exceeded 36 °C (97 °F) the fan was turned on and when it fell below 20 °C (68 °F) the fan was turned off by the dual thermal switch.[34] If the temperature exceeded 50 °C (122 °F) or fell below 0 °C (32 °F), another control thermal switch was activated, changing the duration of the radio signal pulses.[35] Sputnik 1 was filled with dry nitrogen, pressurized to 1.3 atm.[39] For the pressure control the satellite had a barometric switch, activated when the pressure inside the satellite fell below 0.35 kg/cm2 (5.0 psi), changing the duration of radio signal impulse.[39] While attached to the rocket, Sputnik 1 was protected by a cone-shaped payload fairing, with a height of 80 cm (31.5 in) and an aperture of 48 degrees.[21] The fairing separated from both Sputnik 1 and the rocket at the same time when the satellite was ejected.[35] Tests of the satellite were conducted at OKB-1 under the leadership of O. G. Ivanovsky.[28] Sputnik 1 was launched by an R-7 rocket on 4 October 1957. It burned up upon re-entry on 4 January 1958.